One method for detecting defects of an object, in particular of a component, is induction thermography. In induction thermography, by means of an inductor which is guided over the object to be tested (test object), an induction current is excited in the test object. A defect in the test object, particularly in the component, leads to a local disruption of the induction current and consequently to a local change in the heating of the test object by ohmic losses. The change in the local heating is in turn recorded by means of an infrared camera, so that detection of the defects is possible by evaluation of the infrared image that has been recorded by means of the infrared camera.
According to the prior art, the inductors for the testing are arranged at a small distance above the test object. In this case, the maximum amplitude of the induction current excited in the test object lies directly below the conductors of the inductor. This gives rise to the disadvantage that precisely this region that is of interest for the detection of defects is covered by the conductors of the inductor, so that it is scarcely possible to record the region by an infrared camera arranged above the inductor.
Another disadvantage of known inductors is the strong dependency of the induction current at a position of the test object on the distance of the position from the conductor of the inductor. Particularly around the regions with the maximum amplitude of the induction current, this gives rise to an inhomogeneous distribution of the amplitude which makes reliable detection of defects and their size more difficult.